Does anyone know if the circuit boards for these two fob types are interchangeable (this is for a CLK550)?

The reason I ask is that the Mercedes logo fell off from one of my fobs (Version 1), but Version 1 is difficult to find used; Version 2 is a lot easier to find. I just want to take out the circuit board from my original fob (Version 1) and pop it into a new one (Version 2).

 

No, the insides are different. I had to have mine (version 1) replaced last year on my 07 E350 (dropped it in an ice chest), and the dealer gave me a version 2 as a replacement. Here's a picture showing the difference. Version 2 on left, Version 1 on right: https://i.imgur.com/9qzT1i2.jpg I popped them open to show the difference in battery location.

You can however buy an aftermarket version 1 key fob shell, and swap your electronics into that:

 

Also, the Version 2 can't be disassembled without breaking the housing.

 

Right on, thank you for explaining the difference. I know I can buy a different shell, but the aftermarket ones seem to have mediocre reviews (and the real ones on ebay are often in just OK condition and are $60+).

Thanks also for your reply. I can't believe the amount of knowledge you have on, well, everything lol.

By pure luck, I ended up finding the emblem on my garage floor after I posted my question. Therefore, I'm probably just going to get some JB Weld, stick it back on, and call it a day! That's (hopefully) a $5 repair instead of a $60+ repair.